About the most popular conventional 35kv110kv subs

2022-08-06
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Discussion on the transformation scheme of conventional 35kv~110kv transformer substation unattended

with the rapid development of China's national economy and the continuous improvement of people's material and cultural living standards; Power users' demand for electric energy is growing, and their demand for power supply quality is becoming higher and higher. Due to the rapid development of electronics and microelectronics technology, in order to better ensure the quality of power supply and the safety, reliability and economy of power system operation. According to the actual situation in China, a number of conventional 35kv- 110kV substations can be transformed into "four remote" and effective control substations by using the current technology. It is imperative to modernize unattended substations. The author puts forward some concrete suggestions and solutions to the relevant problems and the experience of building unattended substations in our bureau, for the reference and discussion of colleagues

functions of an unattended substation

the main task of the integrated automation system of an unattended substation is to monitor, control and adjust various electrical equipment in the substation and exchange information with other levels. The transformation of conventional substation is mainly based on the traditional relay protection system to cooperate with centralized RTU or distributed RTU to realize the transformation of old substation. Its specific functions include eight parts:

1 normal operation function: mainly data collection and processing function, operation log, 3746 points of RMB dollar central parity reduction in 2015, report generation, management function, operator operation function, data display function, telecontrol communication function, etc

2 safety monitoring function: real time detection and out of limit alarm for various required analog quantities and switching values, including measurement of primary circuit current, voltage and power, protection operation, status of circuit breaker and disconnector, equipment status (such as transformer temperature, circuit breaker air pressure), etc

3 protection function: in case of electric circuit breaking fault, relay protection shall be able to selectively and quickly open the circuit breaker, and store the action condition, action signal, fault information and fault data of the circuit breaker in case of accident, which not only realizes the goal of vehicle lightweight and optimizing fuel economy, but also can be used for post accident analysis

4 electric quantity calculation: the collected electric quantity shall be calculated during analysis and statistics

5 remote control function: the power input of circuit breakers, capacitors and reactors in the whole station can be operated automatically according to the issued command. At the same time, we can know whether the external conditions and safety conditions of each operation can be checked automatically by checking the mechanical property data of the product, and whether the tap adjustment of the transformer and the power input of the capacitor can be adjusted jointly

6 telecontrol function: according to the amount of information required by the master station dispatching, transmit information according to the communication protocol to realize remote signaling and remote adjustment

7 remote control function: it can be commanded by the dispatcher and operated directly to open and close the unattended substation

8 self diagnosis and automatic recovery function: the system itself has the self-tuning function for its hardware and software. The data acquisition system can diagnose the track board level fault, and can automatically recover or remove the local fault when it develops, so as to ensure the normal operation of the system

scheme for transformation design of conventional 35kv~110kv substation

1 primary wiring and its equipment of unattended substation; Therefore, its main wiring shall meet the flexibility of remote control operation and adjustment. Therefore, when the power of the upper voltage level is improved, the main wiring of the next level is simplified. For 35kv~10kv low-voltage side, single section bus should be used

2 primary equipment selection

the reliability and stability of primary equipment have a decisive impact on unattended substation; The selection of primary equipment shall follow the rural substation construction proposed by the Ministry of electric power, It shall be based on the principle of "outdoor type, less land occupation, low cost, safety and reliability, advanced technology, small and compact, simple wiring and reliable use". The equipment selection shall be mainly made in China.

(1) the selection of primary equipment shall consider the selection of domestic fully enclosed switchgear SF6, vacuum switch and SF6 recloser.

(2) As for the original sn-10 type oil less switch, its reliability is poor, so it is inevitable that it will refuse to operate, and the leakage problem cannot be cured, so it should be replaced gradually

(3) the opening and closing of transformer neutral point shall be changed from manual type to electric type

(4) on load voltage regulating switch of transformer shall be digital; The input tap position information and output control shall all directly represent the number of tap position

3 transformation of secondary equipment

in the transformation of secondary equipment, the existing protection devices that are not suitable for unattended operation should be phased out. Unified design methods should be adopted for control, protection and monitoring devices to facilitate reliable operation. The specific planning is as follows:

(1) remote controller; Switches at each side of the main transformer, grounding knife switches at the neutral point of the main transformer, all incoming and outgoing line switches, on load voltage regulating switches, operation reset signals, remote control of DC panel and remote control of switching of important pressing plates

(2) remote signaling quantity includes: switch position signal, neutral point knife switch position signal of main transformer, on load voltage regulating gear position signal, grounding knife switch position signal, protection action signal, fuse monitoring signal, abnormal operation signal, reclosing action signal. When the capacity of the master station is limited, relevant signals can be combined for use without affecting the reflection

(3) remote measurement includes: voltage, current, active and reactive power of main transformer and line, bus voltage, phase voltage, zero sequence voltage, DC bus voltage, voltage and current at low voltage side of all transformers

4 relay protection and automatic device:

(1) microcomputer protection and fault recording shall be considered for new or reconstructed substations. The modification of setting value for the equipment's input and exit of protection shall be performed by remote control

(2) devices with frequency action, such as outgoing line protection, reclosing action protection and direction protection, low cycle load shedding, etc., shall be incorporated into microcomputer memory

planning of three dispatching systems

1 the following principles should be considered in the selection of equipment at the dispatching end

(1) domestic advanced series products should be selected

(2) distributed or centralized network structure should be adopted

(3) the interface should meet the CDT and polling protocols

(4) practical and practical results can be targeted according to the financial situation, and the requirements of development should be fully considered

2 the station end must require:

(1) the RTU series is unified, which is conducive to maintenance

(2) it has good working reliability, short control time, high transmission rate and strong processing capacity

(3) the sampling method shall have cross

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